sed/awk question

Hello SCO folks,

Is there a way to take the following lines:
100001 ASCII_STRING 1000
999999 ASCII STRING 99999
and have output:
100001 1000
999999 99999
^^^^^------ 1000 - 99999 Acceptable 4 to 5 digits only
^^^^^^------------- 100001 - 999999 Acceptable Only 6 digits only

From the examples you give "ASCII_STRING" is separated from the first
block and last block of numbers with one or more spaces with no
spaces after the last block of numbers:

100001 ASCII_STRING 1000$
The search string above is /space_space_*.*space_space_*/ to get all
cases of singe or multiple spaces between the first block of numbers
"ASCII_STRING" and the last block of numbers.